Process of mixing a soluble filler with rubber



Patented Aug. 30, 1921.

1,640,818 PATENT OFFICE.

CHARLES E. CAMPBELL, O1 PITTSBURGH, PENNSYLVANIA, ASSIGNOR T AMERICANGLUE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSAGHII-snrrs;

No Drawing.

The invention relates to an improved proc-' ess of mixing a solublefiller with rubber (either natural or reclaimed) for the purpose ofmaking 'a master batch. I 5 The object of the invention is to obtain ahomogeneous mass in which the filler is properly mixed and incorporatedwith the ruber with little difliculty, in a relatively short time, andby which-the resulting mix? has as little moisture in it as possible.

The process is as follows Ordinary milling rolls are-employed and theyare preferably operated one faster than the other as is customary inrubber milling operations, a speed ratio of one 0nd one half to onebeing a good ratio. .The rubber to be filled is first fed to these rollsand'manipulated by them until it has been thoroughly softened. Inpractice, for this softening step the rolls are run at a normaltemperature preferably less than 100 degrees F. The softening operationordinarily takesfrom 3 to 5 minutes. i After the softening of therubber, while it is still being manipulated by the rolls,

the soluble filler in dry form is the rubber, being thrown into the ightof the rolls. The filler. should be finely pulverized, and I prefer touse a filler consiste in of albuminous matter; and preferably a fi erconsistin of portein derivatives of the albuminoids o tained by thehydrolytic 'decomposition of simple proteins of the albu-, mincidgroup,keratin, collagen and elastin, substantially as describedin myco-pending application filed October 1 3, 1924, Serial No. 746,883, as Ihave found that suchsoluble filler may be used to the best advantage inconnection with the present process, al- 40 though other soluble fillerscan also advantageously be used. 'The filler can be used with the rubberin any desired amount, but I have found that it is perhaps better to usea less relative amount of the filler when it is bein mixed withreclaimed rubber. For ex amp c, with 40 lbs. of natural rubber ,I em-.

ploy 40 lbs. of 'filler and withv lbs. of rub er consisting of 25-lbs.of natural rubber and 25 lbs. of reclaimed rubber, I em- 50 ploy 30 lbs.of filler. A

After the filler has been incorporated by the rolls throughout the mass,which usuall takes 2 to 3 minutes, the rolls are heate preferably to atemperature of between 175 applied to raocnss or rrrxme a SOLUBLE rrnnnawrr'n RUBBER. Application med October 22, 1926. Serial No. 143,521-

and 200 degrees F. In practice, I havev found e temperature of 180degrees F. to be a good working temperature; The rotation of the heatedrolls is continued for mixing the filler with the rubber and during thisrotation the mix is sprayed with water at 00 normal temperature intheform of an exceedingly fine spray amounting to a nebula of moisture.This effect. may be obtained by a spraying machine common; in the tradecapable of throwing a very fine spray. The 05 action of the moisturetogether with the heat operates to dissolve and melt the filler so thatas the mixing operation continues it becomes blended with the rubber andpractically homogeneous with it. The mixing operation in the presence ofmoisture is continued until the mixture or blend has been properleflected, which is determined when the rub er begins to pull and stringat the bight of the rolls, this taking from 6 to 8 minutes. After thisthe spray of water is discontinued and the rotation of the heated rollscontinued for driving the moisture out of the mix. This usually takesfrom 3 to 4' minutes, after which the mass is removed from the rolls inthe usual manner and is ready for use, very little moisure remaining inthe mass and 'no such amount of moisture as will be injuriousin futurevulcanizing operations. I 85.

Having thus fully described my invention, I claim and desire to secureby Letters Patent of the United States I 1. The process of mixing asoluble filler with rubber comprising intimately mixing the rubber andfiller in the presence of heat, v and moisture applied to the mass inthe form of an exceedingly fine spray until the filler has beendissolved and thoroughly incorporated in the mass and afterward expelhngv moisture fromth'e mass.

2. The process of mixing a soluble filler with rubber comprisingintimately mixing the filler in dry pulverized form with the rubber invthe presence of heat, and moisture applied to the mass in the form of anex-,

ceedingl fine spray until-the filler has been dissolve and thoroughlyincorporated in i the mass and afterward expelling moisture from themass. .1 3. The process of-mixin a. soluble filler with rubbercomprising so ening the rubber, adding'the filler in dry pulverized formto the rubber and intimately mixing in the presence of heat, andmoisture applied to the mass in the form ofan' exceedingly fine sprayuntil the 'filler has been dissolved 1 and thoroughly incorporated inthe mass and afterward expelling moisture from-the mass. 4. The processof mixing a soluble filler with rubber comprising, milling the rubberapplying the filler in dry pulverized 'form' the mass in the presence ofheat for -expel ling moisture,

5. The process of mixing a soluble filler with rubber comprisingsoftening the rubberby milling, applying the filler in dry'pul verizedform to the softened rubber during the milling, thoroughly mixing themass by continued milling; in the-presence of heat,-

' and moisture applied tothe mass in the form of an exceedingly sprayuntil the filler has been diss lved'an'd thoroughly incorporated in themass and afterward discontinuing' the application of moisture andcontinue ing the milling of the mass" in the presence of heat forexpelling moisture.

CHARLES H. CAMPBELL.

